Update Steinhardt order parameters

[Eric Harper]

Update API and general cleaning

[Vyas Ramasubramani]

@xiyudu I know you talked about this in the past; it was previously assigned to Richmond so I'm just giving it to you for now. We can always reassign if necessary.

[Chrisy Du]

@vramasub I think we did some part of it during the last hackathon, but it definitely is not complete. You should keep reminding me I should clean it :)

[Vyas Ramasubramani]

Yes I think we did a little bit of it, but probably still quite a bit left. We will keep reminding you as we slowly work through this list of issues.

[Richmond Newman]

Been awhile but what still needs to be done? The codebase I know is no longer against boost and has some fragmentation and ugly duplication to implement different coventions (normalization or not, or rcut or closest can neighbors). The latter I hope was closed since I left the group, (maybe).

[Vyas Ramasubramani]

@newmanr I plan to look into this (with Chrisy) at some point. I think there's still quite a bit of code fragmentation and duplication, which is the main thing that needs to get cleaned up. There have been substantial changes to the rest of freud since we started working on it, so that all needs to get folded in, but basically I think properly setting up a class hierarchy would help clean up a lot of this. I'm not sure what you mean regarding boost though, freud is pretty much done with boost at this point aside from 1 feature that we still need to extract boost from.

[Bradley Dice]

@vramasub Can this issue be closed?

[Vyas Ramasubramani]

We can close this when Pull Request #161 is fully approved and merged.

[Bradley Dice]

This will be merged soon. Closing now.